Drying chamber for drying lumber



NOV. 11, 19.69 R, HlLDBRND 3,477,139

DRYING CHAMBER FOR -DRYING LUMBER Filed Dec. '7, 1967 United StatesPatent 3,477,139 DRYING CHAMBER FOR DRYIN G LUMBER Robert Hildebrand,Nurtinger Strasse 68, Oberboihingen,

Wurttemberg, Germany Filed Dec. 7, 1967, Ser. No. 688,776 Int. Cl. F26113/ 04, 25/06 U.'s. c1. 34-191 p s Claims ABSTRACT OF TH DISCLOSURE meansare provided to regulate the condition of the drying medium. The fan ismounted in the loft so that it may be reversed in position to face ineither one direction or a direction 180 opposed thereto so that bypivoting the fan between is two positions, the direction of circulationthrough the drying room may be reversed.

`The present invention relates to drying chambers, and has particularapplication to a chamber for drying lumber wherein fan means is providedfor circulating the drying medium, preferably air, in a given directionthrough the lumber.

For drying lumber and other materials, it is advantageous to reverse thedirection of air flow from time to time in order to obtain uniformdrying throughout the drying chamber. Prior to the present invention,this has been accomplished by the use of a stationary fan Whosedirection of rotation may be reversed when it is desired to reverse thedirection of the ilow. Such reversible fans have srnall efficiencybecause they must be designed to forward the drying medium in onedirection when rotated in a first direction, and in the oppositedirection when rotated in the opposite direction.

The present invention enables the use of a high-eiiiciency fan or blowerwhich is designed to forward air in only one direction and a reversal ofilow is obtained pivoting the entire fan about an axis, preferably aboutan axis disposed substantially at right angles to the axis of rotationof the fan. The fan is held in one position for predetermined period,for example several hours, and then is rotated 180 and held in theopposite position for a similar period so that the two periods, thedirection of flow is reversed without reversing the direction ofrotation of the blades. The present invention therefore makes itpossible to use fans of simple design .having a high efficiency.

In accordance with another feature of the invention, the fan is an axialfan mounted in a ring which surrounds the fan blades and is providedwith oppositely disposed trunnions or pivot pins mounted in bearings tosupport the fan, one of the pivot pins having a drive wheel securedthereto. The bearings for the fan support may be of simple design topermit pivoting of the fan, or retention of the fan in its adjustedposition, by means of the drive wheel, which is connected, at leastindirectly, with a positioning motor.

To avoid the necessity for a positioning motor, the pivotal axis for thefan may be offset from the rotary axis of the fan blades so that thereaction force produced by the rotation of the fan provides a pivotingforce for pivoting the fan on its trunnions. A stop is provided to haltthe pivotal movement of the fan in the desired position so that byoperation of the stop, the position of the fan may be changed asdesired.

31,477,139 Patented Nov. 1l, 1969 All of the objects of the inventionare more fully set forth hereinafter with reference to the attacheddrawing wherein:

FIG. 1 is a transverse sectional view of a drying chamber embodying thepresent invention;

FIG. 2 is a longitudinal section taken along the line 2-2 of FIG. l;

FIG. 3 is an enlarged sectional view taken on the line 3-3 of FIG. 2;

FIG. 4 is a sectional view taken on the line 4-4 of FIG. 3; and

FIG. 5 is a view similar to FIG. 4 showing a modified embodiment of thepresent invention.

In the embodiment of the invention illustrated in FIGS. 1-4 inclusive,the drying chamber 1, includes side walls 22, end walls 23 having doors24 therein through which the lumber 7 is transported, and a roof 25. Thelumber 7 is stacked on the floor of the drying chamber, for example onpallets 26 by means of conventional vehicles.

In accordance with the invention, the drying chamber is provided withmeans for circulating drying medium through the lumber from one sidethereof to the other for a predetermined period and thereafter forcirculating the dying medium in the reverse direction through thelumber. To this end, the drying chamber is provided with a ceiling 2spaced downwardly from the roof to divide the chamber into a drying room31 and a loft 32 through which the drying medium is circulated. Alongthe opposite sides, the ceiling is spaced from the side walls 22 toprovide flow-through openings 3 and 4, the opening 3 of which is coveredby a heat register S, in the present instance a heat exchanger ofconventional design. 'Ihe air is circulated from one wall to theopposite wall within the drying room 31 and is returned through the loft32. In order to reduce the moisture content of the drying medium, meansis provided at 26 to control the moisture content of the circulatingdrying medium. In its simplest form, the moisture-controlling means mayconsist of dampers operable to exhaust moisture-laden air to theatmosphere and to introduce fresh dry air.

In the loft, the drying medium, in the present instance air7 iscirculated by a series of fans 46, each of which is mounted in anupright partition 13 extending longitudinally of the loft 32 of thedrying chamber 1. Each fan is mounted so it can pivot about an axistransverse to the axis of rotation of its blades so that it may face inopposite directions. When facing as shown in FIG. 2, the air circulationis as indicated by the arrows therein. WhenV the fan reverses to facethe opposite direction, the air circulation is opposite to thatindicated by the arrows.

In accordance with the invention, to permit ready reversal of the flow,each fan 6 is mounted in a fan support ring 8 surrounding the fan blades10 and having spider struts 17 for mounting the drive motor 9 for thefan. At diametrically opposite sides, the ring `8 is journalled in thepartition 13 by means of trunnions or pivot pins 11 and 12. The ring ismounted in an opening 30 in the partition 13 Which corresponds inoutline -to the fan support ring 8. The upper trunnion 11 has a drivewheel 14 mounted within the opening 30 and projecting therefrom, asshown in FIG.. 3 to mesh with a drive pinion 15 carried by the driveshaft of a positioning motor 16 mounted on the partition 13. When themotor is energized, it drives the Wheel 14 to rotate the ring 8 in theopening 30 to thereby control the direction in which the fan faces. Whenthe motor 16 is de-energized, it serves to retain the fan in itsadjusted position.

As shown in FIG. 2, a plurality of fans are provided in the partition13. Although each fan may be provided With a separate positioning motor,it is more advantageous to gang the fans together, for example by meansof a drive chain 27 and sprockets 28 on the individual fan support ringsas shown in FIGS. 2-4. In this way, only a single position motor iSrequired. In the embodiment of the invention illustrated in FIGS. 1-4inclusive, the positioning motor is shown as a conventional rotarymotor, but it should be understood that the positioning motor mayconsist instead of a hydraulic or pneumatic operating cylinder connectedto the fan ring 8 in any convenient manner. Alternatively, the motor maybe omitted and a simple mechanical manual control may be provided forpivoting the fans and locking them in position.

It may be desired to use the reaction force of the fan to supply theturning force for pivoting the fan between its oppositely facingpositions, For example, as Shown in FIG. 5, the fan 6 is mounted in afan support ring 8 having upper and lower trunnions 11 and 12respeclively, whose common axis is disposed offset from the rotary axisof the fan blades 10. The trunnions 11 and 12' mount the fan 6 in anelliptical opening 30' in a partirion 13 corresponding to the partition13 of the previously described embodiment. In order to ll the opening30', the fan support ring includes a crescent-shaped appendage 18 sothat it presents a symmetrical outline relative to the' axis of thetrunnions 11' and 12. Thus, the fan support ring fills the opening 30'in both of its positions which are 180 apart.

Because of the offset relationship of the trunnion axis to the rotaryaxis of the fan 6, the reaction force of the fan tends to rotate the fanassembly on the trunnions 11' and 12. To secure the fan in either of itsoppositelyfacing positions, a stop element 20 projects into the path ofthe fan ring 8 to form a stop, arresting pivotal movernent of theassembly on the trunnions. In the present instance, the stop element 20is made as the armature of a solenoid 19 such that when the solenoid 19is energized, the stop is withdrawn out of the path of the fan ring 8permitting the reaction force of the fan to pivot the assembly on thetrunnions 11' and 12. Upon def-energization of the solenoid 19, the stopelement 20 projects into the path of the fan ring 8 to prevent furtherrotation beyond the 180 pivotal movement afforded by the withdrawal ofthe stop element from the opening 30'. In this manner, the separatepositioning motor is not required, enabling the use of the reactionforce of the fan to provide the pivotal movement, under the control ofthe stop element 20.

In the drying of lumber in a drying chamber in accordance with thepresent invention, the direction of circulation of the drying medium isreversed only at great intervals of time, for example after severalhours. The actuation of the positioning motors, or the Solenoid may beperformed automatically by a suitable timer, or may be performedmanually by the operator.

While particular embodiments of the present invention have been hereinillustrated and described, it is not intended to limit the invention tosuch disclosure, but changes and modifications may be made therein andthereto within the scope of the following claims.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. In a drying chamber having walls, a roof, a ceiling spaced from saidroof to separate said drying chamber into a drying room and a loft, anda fan to circulate drying medium through said drying room in a givendirection, and means to control the condition of said drying medium insaid loft; the improvement wherein said means to circulate the dryingmedium comprises at least one axial fan mounted in said loft, said fanhaving blades mounted for rotation about an axis of revolution, asupport ring surrounding the blades of Said fan and supporting the fanmotor, trunnions transverse to and offset from the axis of revolution ofsaid fan and disposed on a common vertical axis to support said ring forpivotal movement between opposite positions facing respectively inopposite directions whereby in one position Said fan effects circulationthrough said drying chamber in a given direction, and in the oppositeposition said fan effects circulation of the drying medium through saiddrying room in the opposite direction, whereby, upon rotation of saidfan, the reaction forces of said fan tend to pivot said fan ring on saidtrunnions, and means to retain the fan in position comprising a stopelement operable between operative and inoperative positions, in theinoperative position permitting pivotal movement of said fan ring bysaid reaction force's, and in the operative position projecting into thepath of the fan ring to prevent pivotal movement thereof by saidreaction forces and to hold said fan in one of said opposite positions.

2. A drying chamber according to claim 1 wherein said stop constitutesthe armature of a solenoid operable when energized to dispose said stopin its inoperative position and operable when de-energized to disposesaid stop in its operative position.

3. A drying chamber according to claim 1 wherein said loft is providedwith an upstanding partition spanning between said roof and saidceiling, said partition having an opening for said fan ring, saidtrunnions pivotally mounting Said fan ring for pivotal movement in saidopening, said fan ring having an outline symmetrical to the verticalaxis of said trunnions, and said opening conforming in outline to theoutline of said fan support ring.

4. A drying chamber according to claim 3 wherein said opening iselliptical and said fan support ring comprises a circular portionsurrounding the fan blades and a crescent-shaped appendage to conformsaid ring to the elliptical outline of said opening.

5. A drying chamber according to claim 4 wherein the center of saidcircular portion is offset from the vertical axis of said trunnions.

References Cited UNITED STATES PATENTS 1,713,648 5/1929 Feinberg et al.98--29 1,968,874 s/1934 Cobb 34-191 3,149,932 9/1964 Bachrich 's4-191FOREIGN PATENTS 521,005 3/1931 Germany. 260,605 10/1928 Italy.

FREDERICK L. MATTESON, JR., Primary Examiner H. B. MMEY, AssistantExaminer U.S. Cl. X.R. 34-223

